Electric vehicles have been a fast-growing area of interest for the automotive industry in the recent years. One of the issues in electric-motor drive-trains is that they generate significant heat through rotation of the rotor shaft. Traditionally, this heat is dissipated by conducting it through the motor enclosure and gearbox enclosure. From there, both enclosures are cooled by convection.
In the past ten years there have been some efforts at motor cooling which involves the cooling the rotor. However, these efforts have so far proved incompletely satisfactory.
Certain rotor cooling directs liquid into rotor of electric motor from one side of the rotor and have the liquid returning at the same side of the rotor. The liquid has to travel from one side to the other side of the rotor and return back to the liquid inlet side for draining. The drawbacks of this cooling path is the twice long path for the cooling liquid to travel and it only removes the rotor heat generation with additional liquid pressure drop. Also this cooling path does not remove the heat generated in the first stage shaft of the gearbox and the heat generation from the coupling where the electric motor couples with the gearbox.
Therefore, a need continues to exist for a more effective cooling system for electric motors.